Microbes usually don’t live isolated but together with myriads
of other microbes in large communities. Such microbial communities
also live on and in our bodies – like our gut – and are therefore
crucial for our health. Despite the enormous importance of microbial
assemblages for our well-being we have very limited understanding of
how these communities form and function. Our lab aims to reveal basic
principles of microbial communities with a combination of lab experiments
and mathematical modeling. We are especially interested in how we can
understand, describe and predict interactions between microbes (1),
how these interactions shape complex microbial communities (2) and
finally how we can use ecological forces within microbial communities
for medical purposes (3).
1) What determines microbial interactions?
1) What determines microbial interactions?
Microbes strongly influence each other's growth — they interact.
These interactions can be driven in many different ways: microbes
can compete for resources, produce toxins or supply each other
with nutrients. Despite this diversity interactions have very often
one thing in common: they are mediated through the environment.
The outcome of an interaction is determined by how microbes change
their environment and how this change affects their own and others’
growth. With this basic idea we could show that beneficial modifications
of the environment can cause spatial self-organization of microbes
(Ratzke and Gore, Nature Microbiology, 2016). We could further show
that microbes can also change the environment in such detrimental
ways, that whole populations can wipe themselves out
(Ratzke et al., Nature Ecology and Evolution, 2018).
Finally, we were able to understand and predict interactions
between different microbes (Ratzke and Gore, PLOS Biology, 2018).
Our lab wants to extend this direction in the future to develop a
more basic and general understanding of what determines microbial
interactions and how we can predict them.
2) What shapes complex microbial communities?
Interactions between microbes are basic building blocks of
microbial ecosystems. They influence who is present or absent
in the community and therefore set the overall composition,
stability and biodiversity of microbial ecosystems. However,
how all these microbial interactions work together to shape
the overall community remains unresolved. Can we therefore gain
insight into complex communities from studying simple microbial
interactions at all? We could currently show that it is indeed
possible. Thus, we found that the interaction strength can set
the biodiversity and stability of complex microbial communities
(Ratzke et al., Nature Ecology and Evolution, 2020). Encouraged
by these findings we want to further explore what features of
complex communities we can predict from knowing the average
interaction forces within them.
2) What shapes complex microbial communities?
3) Can we use microbial interactions to treat infections? (ERC StG 2020 BugDrug)
We carry a vast number of microbes on our body. Accordingly,
pathogenic microbes that try to infect us have to interact
with the native microbes. These interactions can facilitate
or repel the pathogen and therefore decide whether we get
sick or not. With C. elegans as a model organism we want to
study how interactions within the gut microbiota influence
the course of an infection and how they can protect us from
getting sick. Understanding how interactions between microbes
can prevent microbial infections may open new ways to treat them. This project is supported by a 2020 ERC Starting Grant.
